Ovarian cancer is the fifth leading cause of death from cancer in U.S. women. In most instances, a diagnosis is not made until the cancer is in an advanced state; at a time when the five year survival rate of patients is only about 28% (Ries, et al., SEERC Cancer Stat. Rev. 1973–1995 (1998)). In contrast, the five year survival rate for women diagnosed with localized disease is about 95%. These statistics provide an incentive to search for tests that can be used to identify ovarian cancer at an early stage.
The protein prostasin was originally isolated from human seminal fluid and is present at high levels in the prostate gland (Yu, et al., J. Biol. Chem. 270:13483–13489 (1995); Heid, et al., Genome Res. 6:986–994 (1996)). It is expressed to a lesser extent in the kidney, liver, pancreas, salivary gland, lung and colon (Yu, et al.) J. Biol. 270:13483–13489 (1995); Yu, et al., J. Biol. Chem. 269:18843–18848 (1994)). Its function in these tissues has not yet been determined and a clear association between prostasin and cancer has not been established.